FEDERAL MINISTRY OF WATER RESOURCES FEDERAL REPUBLIC …awdrop.org/wp-content/uploads/2017/01/nigeria-national... · 2017. 2. 7. · federal ministry of water resources. federal republic

FEDERAL MINISTRY OF WATER RESOURCES

FEDERAL REPUBLIC OF NIGERIA

THE PROJECT FOR

REVIEW AND UPDATE OF

NIGERIA NATIONAL WATER RESOURCES

MASTER PLAN

PROGRESS REPORT - 2 SUMMARY

JULY 2012

JAPAN INTERNATIONAL COOPERATION AGENCY

YACHIYO ENGINEERING CO., LTD. CTI ENGINEERING INTERNATIONAL CO., LTD.

SANYU CONSULTANTS INC.

The Project for Review and Update of Nigeria National Water Resources Master Plan

SUMMARY OF PROGRESS REPORT-2

1. Review of Existing Water Master Plan Based on the projects proposed in National Water Resources Master Plan, 1995 (M/P1995) and overall performance of its implementation, the revised and updated version of M/P1995 (Revised M/P) must be prepared considering such things as follows.

National Policies and Basic Strategies of Water Master Plan

M/P1995 takes such water policies shown in “National Long Term Plan, 1992,NPC” into account as 1) Expansion of irrigated agriculture to meet the growing food demand due to population growth, 2) Provision of facilities to supply safe and clean domestic water, and 3) Preservation of the quality of water environment.. Strategies of M/P1995 have been developed along with these basic policies. These policies, still important national water policies, should be retained by Revised M/P in accordance with the latest national plans (Nigeria Vision 20: 2020, Water Sector Roadmap etc.).

Evaluation of Water Resources Potential

In M/P1995, the water resources potential has been evaluated by using the observed flow and rainfall observations of the 1970s and 1980s. At the time, it was the first time to evaluate comprehensive water resources across the country as a whole. However, it has several drawbacks from the viewpoint of appropriate water resources management. For example, regarding the evaluation of surface water potential, 1) Evaluation period using data is short. 2) Potential is evaluated only in average and drought is not evaluated. 3) There is no discussion on flood discharge. In formulating Revised M/P, using long-term observation data (long-term rainfall data is available) as long as possible, evaluation should clarify the flow regime, flood discharge and probability of flow. Regarding the evaluation of groundwater potential, evaluation shall take into account not only meteorological conditions but also hydrogeological conditions of the area.

Demand Projection and Implementation of Water Resources Development Plan

M/P1995 shows water demand to achieve the target of the national plan, but the process to decide final amount of demand which is a base of development plan for water supply and irrigation is not clear. Demand options should be compared based on various development scenarios. As an evaluation of the present, the planned demand seems to be some excessive. About this, it may be said that progress of various projects is late adversely. Water development project (for surface water and groundwater development), water supply project and irrigation project shows the delayed progress. The delay of the project extends to the rehabilitation project for the existing facilities as well as a new project. Although it is pointed out that the project is delayed due to budget shortfall, there seems to a problem with not only budget shortfall but also the project operation systems. About sub-sectors other than water supply and irrigation, there is insufficient discussion in M/P1995 due to the jurisdiction for other ministries.

In recent years, the demands for flood & erosion control and small scale hydropower generation are increasing. In formulation of Revised M/P, discussion on these new demands should be deepened from the viewpoint of “Integrated Water Resources Management (IWRM)”.

Implementation of Water Resources Management Plan

M/P1995 has proposed the foundation of monitoring system to observe the quantity and quality of water resources elements (climate, surface water and groundwater) but its implementation is very late. Since monitoring of water resources is the cornerstone of water resources management, in formulation of Revised M/P, the method of early realization of water resources monitoring system should be examined.

New organizations such as NIHSA and NIWRMC were established changing the form but taking over the spirit of the organization proposed in M/P1995. NIWRMC was established responsible for water resources management. M/P1995 does not mention the contents of water resources management. Revised M/P should discuss the contents of water resources management that NIWRMC should carry out. Also, these new organizations have an important issue addition to existing organizations. One of the challenges is Capacity Development (CD). In addition to CD mentioned above, Revised M/P should discuss the current and important such challenges concerning water resources management as

Progress Report (2) (S-1)


information management, risk management (including drought, flood, cross boundary water), adjustment of water right, conservation of water environment, promotion of PPP, effective application of monitoring and evaluation (M&E) and so on. And Revised M/P should propose the practical measures to realize them.

Conclusion

M/P1995 drew a route to reach a target of important national policy at the time (on water supply and irrigation etc.). Implementation of the projects proposed in M/P1995 does not proceed as scheduled after some 20 years passed from the planning, and it is also difficult to achieve goals at the planning target year (2020).

There are such reasons as 1) Is it correct demand projection? (Water supply unit rate, irrigation scale, cropping pattern, combination with irrigation and rain-fed agriculture etc.), 2) Is it weak implementation structure? (Deficient regulatory & operational system, lack of capacity of human resources, insufficient participation of stakeholder etc.), 3) Is it luck of budget? (Unsuitable project environment: insufficient consensus building, poor project justification note, luck of lobbying for budget acquisition). In preparation of Revised M/P, measures to solve the issues above mentioned, or measures to realize the plans should be examined carefully.

2. Image of Revised Water Master Plan

(1) Revised National Water Resources Master Plan (Revised M/P)

The revised national water resources master plan (Revised M/P) is a plan that the technical cooperation of JICA review and update the current national water resources master plan, 1995 (M/P1995) which was prepared also by the technical cooperation of JICA. Revised M/P, targeting the year of 2030, will be a part of national plan through formal and regal procedures. JICA Project Team prepared a draft of Revised M/P (Draft Revised M/P) in cooperation with Nigerian Counterpart Team. Revised M/P is formulated analyzing available data and information on the basis of the concept of IWRM. Main components of plan are 1) Water Resources Development Plan, 2) Water Resources Utilization Plan (or Sub-sector Development Plan) and 3) Water Resources Management Plan. Refer to Figure S-1.

Source: JICA Project Team

Development Utilization Needs from Users

【Demand】 Water Supply Irrigation Hydropower Gen. Flood & Erosion

Control Inland Navigation Aquaculture Livestock Farming Water Recreation Environment, etc.

Water Resources

【Potential】 Surface Water &

Groundwater Flow Regime Long-term Discharg Probable Drought

Discharge Probable Flood

Discharge Water Head Water Quality, etc.

Administration for Water Resources Development & Utilization through Process of Stakeholder Participation

Integrated Water Resources Management (IWRM)

Based on Sufficiency & Efficiency and Equitability & Sustainability

W.R. Utilization Plan

W.R. Management Plan

W.R. Development Plan

Figure S-1 Image of Revised Water Master Plan

(2) Integrated Water Resources Management ( IWRM）

Integrated Water Resources Management (IWRM) is being recognized internationally as an effective method on the development and management of water resources. IWRM is a process which promotes the coordinated development and management of water, land and related resources in order to maximize economic and social welfare in an equitable manner without compromising the sustainability of vital ecosystems and the environment. IWRM is targeting the following three integrations:



Integrated consideration on natural world: To consider, in an integrated manner, any form and stage of water in natural water cycle such as water resources & land resources, water quantity & quality, surface water & groundwater and soon. Evaluation of Water Resources

Integrated consideration on various sectors related to water: To consider, in integrated manner, various sectors which conventionally have been managed separately. Clarification and Projection of Water Demand

Participation of various stakeholder: To employ participatory approach to stakeholder at all levels including central government, local government, private sectors, NGO and residents Consensus of Stakeholders

(3) Water Resources Development Plan (WRDP)

Water Resources Development Plan (WRDP) plans the approach of water resources development (such as dam/reservoir, intake facility, channel, well and so on) to suffice needs of water users, on the basis of evaluation of water resources potential and projection of users’ demand WRDP plans facilities and also basic operation systems. WRDP targets basically new project for water resources development. If the new water is developed by the change or remodeling of facility and system, this re-development project is planned in WRDP. Also WRDP plans the mitigation measures of flood disaster. Target water resources are generally conventional ones such as surface water and groundwater. But in semi-arid areas, non-conventional ones such as desalinated sea water and reclaimed waste water are targets of development as well as conventional ones. Refer to Figure S-2.

(4) Water Resources Utilization Plan (WRUP)

Water Resources Utilization Plan (WRUP) plans the approach of utilization of facilities and systems to meet demands of such sub-sectors as water supply, irrigation, hydropower generation and so on. This plan is referred as Sector Development Plan (such as Water Supply Plan and Irrigation Development Plan and so on). If WRUP is affected by WRDP, WRUP should be prepared by working closely with WRDP. Refer to Figure S-2.


Projection of Sub-sector(s) Demand

Evaluation of Water Resources Potential

Plan of Water Resources

Utilization for User(s)

Plan of Water Resources

Development for User(s)

Construction

Facilities for WateResources Utilization

Facilities for WateResources

Development

【Users】 Water Supply Irrigation Hydropower Generation Flood Control, etc.

Operation Stage

Plan & Design Stage

W.R. Utilization W.R. Development

Figure S-2 Image of Water Resources Development & Utilization



(5) Water Resources Management Plan (WRMP)

Water Resources Management Plan (WRMP) plans the approach of proper delivery of water services to water users on the basis of sufficiency, efficiency, equitability and sustainability, by using facilities and operation systems which are established by WRDP and WRUP. Flood Management Plan plans to minimize flood damage by operating facilities and systems. A principle of water resources management is to operate facilities and systems on routine process of monitoring – prediction (evaluation) – operation. In addition, it is an important element of water resources management to continue to maintain, repair and improve the facilities and systems for water resources development / utilization / management. Also, WRMP includes the activity plans to support and improve technology and human resources for water resources development / utilization / management. Refer to Figure S-3

< Process of Water Use Management >


Water Flow

On Rule

Operation

Monitoring

River Flow and/or Groundwater (Quality & Quantity)

Facilities for Water Resources

Development

Demand of Water User(s)

Monitoring

Facilities for Water Resources

Utilization

On Rule

Operation

Prediction Monitoring Monitoring

Water Supply Irrigation Hydropower Generation Flood Control, etc.

【Water Users】

Monitoring

Prediction

Operation

Controlled Flow

Monitoring

Prediction

Operation

Controlled Flow

Water Users

ΔT2

δt2 δt3

ΔT1

Water Users

ΔT3 Monitoring

δt1

Controlled Flow

Operation

Prediction

Water Users

Figure S-3 Image of Water Resources Management

(6) Contents of Revised Water Master Plan

Figure S-4 shows the contents of Revised M/P including main three plans: 1) Water Resources Development Plan, 2) Water Resources Utilization Plan (or Sector Development Plan) and 3) Water Resources Management Plans.




National Water Resources Master Plan 2013

INTRODUCTION

Background of Review and Update of National Water Master Plan 1995 Overview of Implementation of National Water Master Plan 1995

FRAMEWORK OF NATIONAL WATER MASTER PLAN 2013 Current Water Issues and Challenges Water Policy and Strategy for National Water Master Plan 2013 Framework of National Water Master Plan 2013

ORGANIZATION AND INSTITUTION Organizations for Water Resources Management and Development Instituional Programs

DEVELOPMENT PLANS MANAGEMENT PLAN

DEMAND PROJECTION Socio-Economic Framework Sector Issues and Challenge Water Demand by Sector: Municipal & Industrial Water Irrigation Water Livestock Water Aquaculture Hydropower Generation Navigation Recreation Flood and Erosion Control Water Environment

Catchment Management Plan Assessment Methods of Water Resources

Potential Monitoring Network Data and Information Management Operation and Maintenance Risk Management of Water Resources

(Drought & Flood Management) Management for Sustainable and

Equitable Water Use (Water Right, Polluter& User to Pay, Water Demand Management)

Global Issues (Climate Change, Trans-boundary Water)

Environmental Management for Water Resources

Promotion of PPP Capacity Development Monitoring and Evaluation

POTENTIAL EVALUATION Meteorological Information Surface Water Groundwater Water Quality Effect of Climate Change

BALANCE between DEMAND SCENARIOS and

DEVELOPMENT SCENARIOS Coordination with Demand Scenarios and Water Development Scenarios

UTILIZATION PLANS Municipal & Ind. Water Supply Irrigation Hydropower Generation, etc.

EVALUATION OF UPDATED WATER MASTER PLAN

IMPLEMENTATION PROGRAM including Time Schedule & Financial Program

W. R. DEVELOPMENT PLANS Dam and Reservoir Intake and Pipeline, etc.

Figure S-4 Contents of Revised Water Master Plan

Table S-1 shows the contents of Revised M/P and comparison between Revised M/P and Progress Report (2). The Contents of Revised M/P proposed by JICA Project Team is the draft contents of the official National Water Resources Master Plan. This official document is to be prepared by JICA and FMWR within a half year. The draft contents of Revised M/P will be modified (To be added and/or deleted) if necessary after checking by the Steering Committee for the Project according to the standard of official document. The policy and criteria are explained in the 2nd Steering Committee Meeting, and are discussed in Progress Report (2). The comment of the Steering Committee is requested to be given to JICA Project Team if any before the starting time of Phase-2 of the Project. If there is no big change of content, “Contents of Revised Master Plan” will be concluded at the time. Refer to Table S-1.



Table S-1 Comparison of Contents between Revised M/P and PR-2 Contents of Revised M/P Discussion in PR-2

FOREWORD: Message from the Minister of FMWR CHAPTER 1 INTRODUCTION Background of the Project Chapter-1.1 Overview of Implementation of National Water Master Plan 1995 Chapter -2 Framework of Revised National Water Resources Master Plan Chapter -3 CHAPTER 2 POLICY AND STRATEGY ON WATER RESOUECES

MASTER PLAN

Current Water Issues and Challenges Water Policy and Strategy for Revised Water Master Plan

Chapter-3.1, 3.3 and Chapter-7 & 8

CHAPTER 3 ORGANIZATION Institutional Framework Legal Framework Chapter-3.1

CHAPTER 4 PROJECTION OF WATER DEMAND Future Socio-Economic Framework Chapter-4.1 Municipal and Industrial Water Chapter-4.2 Irrigation Water Chapter-4.3 Demand of Other Sectors Chapter-8.3 CHAPTER 5 EVALUATION OF WATER RESOURCES POTENTIAL Meteorology Chapter-5.2 Surface Water Chapter-5.3 Groundwater Chapter-5.4 Water Quality Chapter-5.3 & 5.4 CHAPTER 6 WATER BALANCE BETWEEN DEMAND AND SUPPLY Balance of Surface Water Chapter-6.3 Balance of Groundwater Chapter-6.4 CHAPTER 7 WATER RESOURCES DEVELOPMENT PLANS Surface Water Development Plans Chapter-3.3 & 7.1 Groundwater Development Plans Chapter-3.3 & 7.2 Water Resources Conservation Plans Chapter-3.3 & 7.3 CHAPTER 8 WATER RESOURCES UTILIZATION PLANS Water Supply and Sanitation Plans Chapter-3.3 & 8.1 Irrigation and Drainage Development Plans Chapter-3.3 & 8.2 Proposal Plans for Other Sub-Sectors: including ■Hydropower Generation, ■Measures for Flood and Erosion, ■Inland Navigation, ■Livestock, ■Inland Fishery

Chapter-3.3 & 8.3

CHAPTER 9 WATER RESOURCES MANAGEMENT PLANS Integrated Water Resources Management Plan Chapter-3.2 Assessment Methods of Water Resources Potential Chapter-5 Monitoring Network Chapter-3.2 Data and Information Management Chapter-3.2 Operation and Maintenance: for ■Water Supply & Sanitation, ■Irrigation, ■Dam

& Reservoir, ■Well Chapter-3.2

Risk Management of Water Resources: regarding ■Drought, ■Flood, ■Climate Change, ■Cross Boundary Water Chapter-3.2

Management for Sustainable and Equitable Water Use Chapter-3.2 Environmental Management for Water Resources Chapter-3.2 Promotion of Public Private Partnership (PPP) Chapter-3.2 Capacity Development for Water Resources Management Chapter-3.2 Monitoring and Evaluation for Water Services Chapter-3.2 CHAPTER 10 IMPLEMENTATION PROGRAM Implementation Agency for Each Project Financial Program and Implementation Schedule Not discussed in PR(2)

CHAPTER 11 EVALUATION OF WATER RESOURCES MASTER PLAN Evaluation: technical, economic, financial, social & environmental view points Not discussed in PR(2)




3. Water Demand Projection

3.1 Population (1) Estimated Population of 2010

This Project applied the 2010 population of Nigeria is estimated by the United Nations in “The 2010 Revision of World Population Prospects” provisionally as a base year population for the projection.

(2) Projected Population up to 2030

The future population of Nigeria is under the projection. However, “Road for Nigeria Water Sector, January 2011, FMWR” estimates the future population of Nigeria as presented in Table S-1.

Table S-1 Estimated Population of Nigeria by FMWR Year 2020 2025 2050

Population of Nigeria 210 million 225 million 389 million Source: Road for Nigeria Water Sector, January 2011, FMWR

Meanwhile, the “The 2010 Revision of World Population Prospects” of the United Nations projected the 3 different cases of future national population of Nigeria as presented in Table S-2 and Figure S-5. It is obvious that the Case-2, median case, is similar to the estimated population of FMWR. Accordingly, based on the Case-2, this Project provisionally projected the future population until the target year of 2030 as shown in Table S-3.

Table S-2 Projected Population of Nigeria by United Nations (People in million) Population 2010 2015 2020 2025 2030 2050

Population 158.4 181.1 207.6 237.1 269.2 433.2Case-1 High (Growth Rate) - (2.72%) (2.77%) (2.69%) (2.58%) (2.41%)

Population 158.4 179.7 203.8 229.7 257.8 389.6Case-2 Median (Growth Rate) - (2.56%) (2.55%) (2.42%) (2.33%) (2.09%)

Population 158.4 178.4 200.0 222.4 246.3 348.3Case-3 Low (Growth Rate) - (2.41%) (2.31%) (2.15%) (2.06%) (1.75%)

Source: “The 2010 Revision of World Population Prospects” of the United Nations

100

150

200

250

300

2010 2015 2020 2025 2030

(Year)

(mill

ion

Case-1 (High)

Case-2 (Median)

Case-3 (Low)


Figure S-5 Projected Population of Nigeria from 2010 to 2030

Figure S-6 and S-7 show geographically LGA-wise population of 2010 and 2030, and also population density in Figure S-8 and S-9.

Table S-3 Census and Projected Population (People in thousands) Census 1) Estimate2) Estimate 2) 1991 2006 2010 2015 2020 2025 2030

Nigeria 88,992 140,432 158,423 179,791 203,869 229,796 257,815Growth Rate - 3.18% 3.06% 2.56% 2.55% 2.42% 2.33%

Note: Projection from 2015 is a figure of the Case-2 (median growth). Source: 1) NPC - Census, 2) United Nations



Source: JICA Project Team Figure S-6 GIS Map of Estimated Population by LGA in 2010

Source: JICA Project Team Figure S-7 GIS Map of Estimated Population by LGA in 2030



Source: JICA Project Team Figure S-8 GIS Map of Estimated Population Density by LGA in 2010

Source: JICA Project Team Figure S-9 GIS Map of Estimated Population Density by LGA in 2030



3.2 Municipal and Industrial Water (1) Process and Conditions of Water Demand Projection

(1-1) Flowchart of Water Demand Projection

Figure S-10 shows flowchart of water demand projection.


Commercial Water Daily Consumption

Per Capita Consumption

Service Population

Population in the Target Area

Daily Average Consumption

Daily Average Water Demand

Water Loss

Daily Maximum Factor

Daily Maximum Water Demand

Water Supply Coverage

Domestic Water Daily Consumption

Industrial Water Daily Consumption

Other Water Daily Consumption

Figure S-10 Flowchart of Water Demand Projection

(1-2) Domestic Water

Daily average domestic water consumption is calculated by multiplying population served by per capita consumption (lit/cap/day).

a) Categorization of Settlement and Categorization on Water Demand Projection

However, water demand projection by settlement category based on population size only may cause inaccuracy because there is mixture of various water supply schemes, various living or water usage situations, and various income groups on the ground in settlement. In the process of water demand projection, this Project put additional category shown in Table S-4 and allocate population based on referenced indicators such as household using flush toilet.

Table S-4 Categorization of Settlement and Categorization on Water Demand Projection Population Size Settlement Category Typical Water Supply Scheme Category on Water Demand Projection1 More than

20,000 Urban Surface water, piped supply,

house or yard connection Urbanized water usage (referenced indicator: household using flush toilet)

2 5,000 to 20,000 Semi-Urban or Small Town

Surface or groundwater, small scale piped supply, communal tapstands, house or yard connection

Semi-urbanized water usage (except the above 1 and the below 3)

3 Less than 5,000 Rural Ground water, 250m radius, 250-500 persons per point

Ruralized water usage (referenced indicator: household using hundpump)


b) Water Supply Coverage

National water supply coverages of 75% in 2015 as midterm goal and 100% in 2025 as long-term goal specified in the Sector Roadmap 2011 by FMWR are considered as guidepost. But, water supply coverage in each target year should be practically set by the above settlement categories based on population size, because the necessity of water supply infrastructure development is dependent on socioeconomic activities.



This Project utilizes the water supply coverages by settlement category at the State level, published by the results of Core Welfare Indicators Questionnaire Survey (CWIQS), 2006 in order to estimate the present water demand, and then applies them respectively as an average to the local government areas across the board in each State.

Summation of water consumption by LGA on the basis of the above supply coverages and 100% attainment in 2025 with constant improvement of supply coverage resulted in national water supply coverage of 56% in 2010, 71% in 2015 and 85% in 2020 as each target coverage.

On the assumption that development and improvement are not carried out as planned, sensitivity analysis includes the scenario in which national water supply coverage is a variable.

Table S-5 National Water Supply Coverage by Settlement Category in Target Years (Provisional) National Water Supply Coverage Target Year Nationwide Urban Semi-Urban, Small Town Rural

2010 (Current) Estimated by this Project 56％ 72% 51% 40%

2015 71% 81% 68% 60% 2020 85% 91% 84% 80% 2025 100% 100% 100% 100% 2030 100% 100% 100% 100%


c) Population Served

Based on the above coverage, this Project estimates population served shown in Table S-6;

Table S-6 Population Served by State and Hydrological Area (HA) Population Served (1,000 persons) Items 2010 2015 2020 2025 2030

National Population Served 79,848 120,287 170,100 229,796 257,815Source: JICA Project Team

d) Per Capita Consumption of Domestic Water

In view of the present water supply coverage and high growth of water demand by increase in population, although revision of the per capita consumption should be considered due to possibility of future improvement in living standards, progress of the coverage should be above everything else. So, this Project applies current standard per capita consumption shown in Table S-7 until 2030, the target year of the M/P.

Table S-7 Per Capita Consumption of Domestic Water Settlement (Water Supply) Category Category on Water Demand Projection Per Capita Consumption 1 Urban Urbanized water usage 120 lit/cap/day 2 Semi-Urban or Small Town Semi-urbanized water usage 60 lit/cap/day 3 Rural Ruralized water usage 30 lit/cap/day

Source: Federal Ministry of Water Resources (FMWR)

(1-3) Commercial Water

Daily average commercial water consumption is provisionally calculated at the ratio of 10% of daily average domestic water consumption across the board at the State level except 20% for Kano, Lagos States and FCT Abuja, because useful reference data have not been confirmed. These ratios are referred to instances from Japan, the Philippines (Manila), Colombia (Bogota), Indonesia (Bali) and Brazil (Sergipe). The Project will continue to ascertain information.

(1-4) Industrial Water

Daily average industrial water consumption is provisionally calculated at the ratio of 1.25% of daily average domestic water consumption in the Northern area, 2.5% in the Southern area and 5.0% in Kano and Lagos States, because useful reference data have not been confirmed.

As well as commercial water, these ratios are referred to instances from Japan, the Philippines (Manila), Colombia (Bogota), Indonesia (Bali) and Brazil (Sergipe). The Project will continue to ascertain information.



(1-5) Other Water

Other water is, for example, in-house usage water for water supply services by State Water Agencies and insensible water caused by metering inaccuracies and so on. It has normally a very little proportion of total water consumption, so it can be regarded as being included in commercial water or water loss described below.

(1-6) Water Loss

Water loss is defined as total volume of water leakage from pumping equipment, reservoirs and pipelines, and also missing water by illegal connections, that is, synonymously unaccounted for water (UFW). But, most of State Water Agencies can not figure out water loss ratio accurately because flat rate tariff is much more common in urban, semi-urban and small town water supplies in Nigeria, which means almost no water meter installation. Furthermore, poor data management of existing facilities causes difficulty of status analysis. In view of these facts, 30% of water loss ratio is provisionally applied across the board except rural water supply.

At the prospect of replacement of aged or damaged pipes, improvement of revenue water through water demand management, sensitivity analysis includes the scenario in which water loss rate to be reduced expectantly is a variable.

(2) Result of Water Demand Projection

Table S-8 and Figure S-11 shows results of nationwide water demand projection, based on the above basic conditions. The estimated nationwide water demand will nearly triple from 2010 to 2030. Figure S-12 and S-13 shows geographically estimated water demand by LGA of 2010 and 2030.

Table S-8 Water Demand Projection Water Demand (m3/day) Items 2010 2015 2020 2025 2030

2030/2010 Ratio

Nationwide 8,377,481 11,855,899 16,132,632 21,253,961 23,903,637 2.9 Source: JICA Project Team

0

5,000

10,000

15,000

20,000

25,000

30,000

2010 2015 2020 2025 2030(Year)

(1,0

00m

3/da

y)

Water Demand


Figure S-11 Result of Nationwide Water Demand



Source: JICA Project Team Figure S-12 GIS Map of Estimated Water Demand by LGA in 2010

Source: JICA Project Team Figure S-13 GIS Map of Estimated Water Demand by LGA in 2030



(3) Sensitivity Analysis on Water Demand Projection

(3-1) Conditions of Scenarios

In consideration of water demand subject to management of water demand and realistic aspect of water supply coverage, this Project compares the water demand projection based on the above basic conditions with other alternative projections in the following 3 scenarios.

Basic Scenario : Water demand projection based on basic conditions This scenario based on basic conditions described above is provisionally positioned “Basic Scenario” in the M/P to be revised.

Scenario-1 : Water demand projection based on basic conditions with the exception that water supply coverage of 2025 cannot be attained. On the assumption that infrastructure development does not progress as planned, this scenario makes nation-wide water supply coverage down at 89% in 2025 and100% in 2030, the target year of the M/P to be revised.

Scenario-2 : Water demand projection based on basic conditions with the exception that water loss ratio is reduced from 30% to 10% until 2030 On the assumption that water demand management and measures against non-revenue water are carried out effectively, this scenario makes nationwide water loss ratio reduced from 30% to 10% in stages until 2030.

Scenario-3 : Water demand projection based on same basic conditions as Scenario-1, with the exception that water supply coverage of 2025 cannot be attained and also water loss is improved from 30% to 10% in 2030 This scenario is combination of both Scenario-1 and Scenario-2.

Table S-9 shows conditions of the above 4 scenarios.

Table S-9 Condition Setting for Sensitivity Analysis Items Basic Scenario Scenario-1 Scenario-2 Scenario-3

Domestic Water Per Capita Consumption Urban 120 lit/cap/day 120 lit/cap/day 120 lit/cap/day 120 lit/cap/day Semi-Urban and Small Town 60 lit/cap/day 60 lit/cap/day 60 lit/cap/day 60 lit/cap/day Rural 30 lit/cap/day 30 lit/cap/day 30 lit/cap/day 30 lit/cap/day

Commercial Water (Ratio to Domestic) 10%, 20% 10%, 20% 10%, 20% 10%, 20% Industrial Water (Ratio to Domestic) 1.25%, 2.5%, 5% 1.25%, 2.5%, 5% 1.25%, 2.5%, 5% 1.25%, 2.5%, 5% Water Supply Coverage Nationwide 2010 56% 56% 56% 56% 2015 71% 67% 71% 67% 2020 85% 78% 85% 78% 2025 100% 89% 100% 89% 2030 100% 100% 100% 100% Urban 2010 72% 72% 72% 72% 2015 81% 79% 81% 79% 2020 91% 86% 91% 86% 2025 100% 93% 100% 93% 2030 100% 100% 100% 100% Semi-Urban and 2010 51% 51% 51% 51% Small Town 2015 68% 64% 68% 64% 2020 84% 76% 84% 76% 2025 100% 88% 100% 88% 2030 100% 100% 100% 100% Rural 2010 40% 40% 40% 40% 2015 60% 55% 60% 55% 2020 80% 70% 80% 70% 2025 100% 85% 100% 85% 2030 100% 100% 100% 100% Water Loss 2010 30% 30% 30% 30% * Except Rural 2015 30% 30% 25% 25%

Water Supply 2020 30% 30% 20% 20% 2025 30% 30% 15% 15% 2030 30% 30% 10% 10%




(3-2) Results of Sensitivity Analysis and Comparison of Scenarios

Table S-10 and Figure S-14 show results of sensitivity analysis of nationwide water demand projections based on the conditions in the above Table S-9, and also ratio of each scenario to the Basic Scenario.

Table S-10 Results of Sensitivity Analysis of Nationwide Water Demand Projections Estimated Water Demand (m3/dau) and Ratio (%) Items 2010 2015 2020 2025 2030

(I) Basic Scenario Water Demand 8,377,481 11,855,899 16,132,632 21,253,961 23,903,637(2) Scenario-1 Water Demand 8,377,481 11,264,335 14,786,141 18,966,766 23,903,637

Ratio to Basic Scenario (2)/(1) 100.0% 95.0% 91.7% 89.2% 100.0%(3) Scenario-2 Water Demand 8,377,481 11,147,204 14,347,939 17,964,462 19,242,599

Ratio to Basic Scenario (3)/(1) 100.0% 94.0% 88.9% 84.5% 80.5%(4) Scenario-3 Water Demand 8,377,481 10,588,263 13,140,778 16,011,752 19,242,599

Ratio to Basic Scenario (4)/(1) 100.0% 89.3% 81.5% 75.3% 80.5%Source: JICA Project Team

0

5,000

10,000

15,000

20,000

25,000

30,000

2010 2015 2020 2025 2030

(1,0

00m

3/da

y

Basic Scenario

Scenario-1

Scenario-2

Scenario-3


Decrease by Extension of 100% Attainment of Coverage

Decrease by Reduction of Water Loss

Figure S-14 Result of Sensitivity Analysis of Nationwide Water Demand Projections

Comparison of Scenario-1 with Basic Scenario

Differences are water supply coverages of each year and target year of 100% attainment, but water demand of 2030 is same. Compared with Basic Scenario, decrease in water demand is respectively 5% in 2015, 9% in 2020 and 11% 2025.


Difference is reduction of water loss. Compared with Basic Scenario, water demand decreases gradually since 2011 and finally 20% of scale-down is possible in 2030.


Differences are water supply coverages of each year and target year of 100% attainment, and also reduction of water loss. Although 20% of scale-down of water demand in 2030 is same as one of Scenario-2, water demand between 2010 and 2030 is the lowest in all scenarios.

These indicate that decision about water supply coverage and target year of 100% attainment has an effect on water supply development plan, its feasibility and reasonability, and also reduction of water loss can make water demand decreased by water demand management including measures against non-revenue water.

In preparation for revision of M/P, the Project will review basic conditions and weigh possible scenarios, and then make water demand projection more practical to be proposed.



3.3 Irrigation Water (1) Planning Policy on Irrigation Development

Keys of Nigerian agricultural and irrigation policies are (a) enhanced agricultural productivity, (b) expanded irrigated farmland, and (c) internal reform of irrigated farming. The planning policies to develop irrigated farmland under this M/P, based on Nigerian development policies of agricultural and irrigation sectors, are as follows.

Completion of ongoing schemes for irrigation development and rehabilitation, Expansion of rain-fed farmland, Development of new irrigated farmland, Increased rice production, and Creation of employment opportunity

Tables S-11, S-12 and S-13 show two scenarios of development. In addition, it is projected that 50% of the national rice self-sufficiency in 2030 will be attained by both the projected expansion of the rain-fed farmland and the unit yield increase owing to improved farming technologies, even if the national population increases as projected (See the Reference Scenario).

Table S-11 Development Scenarios of the Irrigation Sector Scenario Population Target Plan

Current Year-2010 158 Million

Planted area of main crops: 21 million ha

Self-sufficiency ratio of rice: 50%

N.A

Scenario No.1

Year-2030

To increase both rain-fed and irrigated farmlands

To increase the planted area by half to approx. 30 million ha.

Self-sufficiency ratio of rice: 100%

Completion of ongoing schemes for irrigation development and rehabilitation,

Increased rain-fed farmland area by 1.5%/yr,

Increased production of rain-fed paddy and upland rice by 3.0%/yr,

Increased irrigated farmland area by 16.34%/yr, and

Increased private small-scale irrigated land area by 4.0%/yr.

Scenario No.2

Year-2030

240 Million To increase both rain-fed and

irrigated farmlands To double the planted area to

approx. 4 million ha. Self-sufficiency ratio of rice

(incl. exporting): 150%

Completion of ongoing schemes for irrigation development and rehabilitation,

Increased rain-fed farmland area by 2.0%/yr,

Increased production of rain-fed paddy and upland rice by 3.0%/yr,

Increased irrigated farmland area by 18.86%/yr, and

Increased private small-scale irrigated land


Table S-12 Planned Area and Employment Opportunity on Scenario (1000ha) Scenario Planned Area System Developed Area Irrigated Service

Total 692 306 255 Current Employ opportunity 76.3 million people (48%) ---8,000persons/10,000ton Total 1,535 1,535 1,535 Scenario

No.1 Employ opportunity Perspective: 130.3 million people (54%)---8,000persons/10,000ton Total 3,405 3,405 3,405 Scenario

No.2 Employ opportunity Perspective: 179.4 million people (75%)---8,000perosons/10,000ton Note 1) The Project is supposed to end in year 2013. 2) The planted area is as of year 2008. Source: JICA Project Team



Table S-13 Agricultural Productions on Scenario (,000ha) Scenario Planted Area Production

Current Rice (Total) 1,801 3,470 Other (Total) 19,485 91,877 Grand Total 21,286 95,347 Scenario No.1 Rice (Total) 4,199 11,100 Other (Total) 27,037 151,751 Grand Total 31,236 162,851 Rate to current 147% 171% Scenario No.2 Rice (Total) 5,508 16,599 Other (Total) 40,001 207,645 Grand Total 45,509 224,244 Rate to current 214% 235%

Note 1) Planted area is as of year 2008. 2) Unit yield (t/ha) is 20% more than year 2010. 3) The yield of rice is grain yield. Source: JICA Project Team

Scenario No.1

Areas of rain-fed farmland and irrigated paddy to attain 100% of rice self-sufficiency in the target year 2030

Table S-14 Projected Farmland Area and Yield of Rice in Year 2030 Area Planned (ha) Unit Yield (t/ha) Yield (thousand tons)Rain-fed upland rice 977,000 1.9 1,856 Rain-fed paddy rice 2,382,000 2.4 5,717 Irrigated paddy rice (additional) 249,000 4.2 1,045 Irrigated paddy rice (Public + Private + Fadama) × 70%

591,000 4.2 2,482

Total 4,699,000 11,100 The total area of irrigated paddy nationwide is: 249,000 + 591,000 = 840,000ha Also, the total area of irrigated farmland to be newly developed, including the area planted other crops than rice, is: 840,000 / 0.7 = 1,200,000 ha

Scenario No.2

Areas of rain-fed farmland and irrigated paddy to attain 150% of rice self-sufficiency in the target year 2030

Table S-15 Projected Farmland Area and Yield of Rice in Year 2030 Area Planned (ha) Unit Yield (t/ha) Yield (thousand tons)Rain-fed upland rice 977,000 1.9 1,856 Rain-fed paddy rice 2,382,000 2.4 5,717 Irrigated paddy rice (additional) 1,558,000 4.2 6,545 Irrigated paddy rice (Public + Private + Fadama) × 70%

591,000 4.2 2,482

Total 5,508,000 16,600 The total area of irrigated paddy nationwide is: 1,558,000 + 591,000 = 2,149,000 ha Also, the total area of irrigated farmland to be newly developed, including the area planted other crops than rice, is: 2,149,000 / 0.7 = 3,070,000 ha

Reference Scenario

Acreage of rain-fed farmland and irrigated paddy necessary to retain 50% of the national rice self-sufficiency in the target year 2030

It is concluded from the simulation that no expansion of irrigated paddy is necessary to attain 50% of the national rice self-sufficiency in year 2030, given that the acreages of rain-fed rice fields in both upland and paddy keeps increasing 3.0% a year and that the unit yield increases by 20% due to farming technology improvements.



(2) Cropping Patterns of Hydrological Basins

(2-1) Cropping Calendar

The following figure shows cropping seasons in the three large hydrological basins of Nigeria, which are gained from various materials and interview surveys.

Crop (Area, season) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Rice (Northern, wet)

Rice (Central, Southern)

Grain & vegetables

Figure S-15 Cropping Calendars

(2-2) Current Cropping Pattern

The following table shows the current cropping rate set based on RBDA’s materials and cropping acreages of large-scale irrigation schemes.

Table 3-16 Current Cropping Pattern (%) Irrigation scheme (%) Small-scale private irrigation (%)

Wet Season Dry Season Wet Season Dry Season HA Paddy Upland Paddy Upland Paddy Upland Paddy Upland

1 30 70 0 80 10 70 0 70 2 20 80 0 40 10 70 0 70 3 10 90 10 40 10 70 0 70 4 40 60 0 30 10 70 0 70 5 90 10 20 30 30 50 0 70 6 10 90 0 40 10 70 0 70 7 60 40 20 20 30 50 0 70 8 50 50 0 20 10 70 0 70

(2-3) Cropping Acreage Plan

The following table shows the proposed cropping pattern.

Table 3-17 Proposed Cropping Pattern (%)

Note that the above cropping plan will be further considered in this M/P from now on.

Irrigation scheme (%) Small-scale private irrigation (%) Wet Season Dry Season Wet Season Dry Season HA

Paddy Upland Paddy Upland Paddy Paddy Upland Paddy 1 40 60 0 50 10 75 0 75 2 50 50 20 60 10 75 0 75 3 50 50 20 60 10 75 0 75 4 50 50 20 60 10 75 0 75 5 80 20 50 30 30 55 0 75 6 80 20 50 30 10 75 0 75 7 80 20 50 30 30 55 0 75 8 40 60 0 50 10 75 0 75

(3) Water Demand

The calculation flow to estimate the water demand is shown as follows:




(1) Evapotranspiration

(3) Consumptive Use

(2) Crop Coefficient

Percolation, Water for Land Preparation

(4) Effective Rainfall

(5) Net Water Requirement

(5) Gross Water Requirement

(6) Unit Water Requirement

Surface Water: Conveyance Loss + Irrigation Efficiency =50%

Groundwater: Irrigation efficiency =60%

Existing/ Proposed Cropping Pattern

Water Demand

Area of Farm Land

Water Resources

Figure S-16 Calculation Flow of Water Demand Projection

(3-1) Reference Evapotranspiration The Hamon method, which needs daily mean temperature and day length, is applied in this Project.

Table S-18 Reference Evapotranspiration (mm) HA JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC1 83 94 135 160 168 146 130 117 112 117 95 832 98 105 131 135 132 115 111 105 100 105 100 953 91 98 130 135 134 116 111 106 99 105 97 894 99 105 130 129 127 113 111 106 101 105 102 965 107 108 126 122 122 111 108 105 102 106 107 1066 109 110 128 123 124 112 108 104 102 107 108 1077 108 108 125 120 122 111 109 106 103 107 107 1068 75 84 122 149 161 144 128 114 110 112 90 76

(3-2) Crop Coefficient

The crop coefficients temporally used are the same values as those used in 95M/P, hereafter they will be further considered in this M/P.

Table S-19 Crop Coefficient Crop development period Crop growing

stages

Initial period (Sowing/fix

planting) (Early growing

period) (Growing)Mid-season

(Later growing)

Later growing (Maturity/ harvesting)

Wet/ Dry season May/ Nov Jun/ Dec Jul/ Jan Aug/ Feb Sep/ Mar Rice 0.50 1.03 1.16 0.98 0.14 Other cereal 0.25 0.77 0.98 0.87 0.3

Note: Crop development period is divided into 2 periods for more precise estimation of evaportanspiration.

(3-3) Consumptive Use of Water

The consumptive use of water is estimated using reference evatranspiration (ETo), crop coefficient (kc), deep percolation (Per), and water for land preparation (Pre). The loss due to deep percolation is assumed to be at 2 mm/day in this calculation, and the losses of water due to land preparation are assumed to be 150mm in paddy and 60mm in upland field respectively; paddy needs more water than upland field because pudding is necessary for land preparation.

Crop Evapotranspiration (ETc) = ETo × kc Consumptive Use of Water = ETc + Per +Pre



(3-4) Effective Rainfall

As for paddy, approximately 80% of the total precipitation is often regarded as the effective rainfall if daily precipitation is 5 to 80mm. Accordingly, this M/P adopts 80% for the effective rainfall in paddies. Unlike the paddy, meanwhile, the upland field has no function to store rainfall and the effective rainfall in upland fields is calculated to be smaller than that in paddies. Therefore, this M/P adopts 70% for the effective rainfall in upland fields.

Table S-20 Effective Rainfall (Paddy) (mm) HA JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC1 0 0 2 6 27 61 211 151 89 9 1 02 2 0 11 37 97 132 152 182 190 55 2 13 0 0 7 34 87 114 172 201 155 52 3 04 1 0 16 52 127 147 162 197 208 99 7 05 6 0 55 102 184 249 223 179 276 190 33 56 4 0 42 88 139 177 132 67 166 126 20 37 4 0 63 117 199 240 250 243 277 222 34 48 0 0 1 5 22 46 114 147 59 5 0 0

Table S-21 Effective Rainfall (Upland) (mm) HA JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC1 0 0 1 4 19 43 148 106 62 6 1 02 1 0 8 26 68 92 106 127 133 39 1 13 0 0 5 24 61 80 120 141 109 36 2 04 1 0 11 36 89 103 113 138 146 69 5 05 4 0 39 71 129 174 156 125 193 133 23 46 3 0 29 62 97 124 92 47 116 88 14 27 3 0 44 82 139 168 175 170 194 155 24 38 0 0 1 4 15 32 80 103 41 4 0 0

(3-5) Net Water Requirement, Conveyance, Application Efficiency, and Gross Water Requirement

The net water requirement is calculated by deducting the effective rainfall from the consumptive use of water. Public irrigation schemes take surface water as major water sources. Meanwhile, Fadama farming and some small-scale private irrigation systems in floodplains mainly use sub-surface flows, which occur after flood recession. The other small-scale private irrigation systems outside floodplains have irrigation water mainly by extracting groundwater.

For surface water irrigation schemes, one must calculate the gross water requirement by making allowances for conveyance efficiency from the intake to fields and the application efficiency in the field. As for groundwater irrigation schemes, meanwhile, one only needs to take the application efficiency into account. The irrigation efficiency, which is the product of conveyance efficiency and the application efficiency, is generally estimated as follows.

Surface Water: Conveyance efficiency × Application efficiency = 50% Groundwater: Application efficiency =60%

Hence, dividing the net water requirement by the irrigation efficiency gives gross water requirement.

(3-6) Diversion Water Requirement

The following diversion water requirements are calculated from gross water requirements and the cropping patterns. It is presumed that farmers in HA-1 and 8 do not grow paddy rice in the dry season because of less precipitation. Consequently, the plan shows net water requirements for paddy rice in those areas are zero in the dry season.



Table S-22 Surface Water: Diversion Water Requirement (Current) Net Water

Requirement (mm) Gross Water

Requirement(m3/ha)Cropping Pattern

(%) HA Season Paddy Upland Paddy Upland Paddy Upland

Diversion Water Requirement

(m3/ha) Wet 440 152 8,800 3,000 30 70 4,740 1 Dry 0 350 0 7,000 0 80 5,600 Wet 262 28 5,200 600 20 80 1,520 2 Dry 787 373 15,700 7,500 0 40 3,000 Wet 272 42 5,400 800 10 90 1,260 3 Dry 771 359 15,400 7,200 10 40 4,420 Wet 203 3 4,100 100 40 60 1,700 4 Dry 782 370 15,600 7,400 0 30 2,220 Wet 87 0 1,700 0 90 10 1,530 5 Dry 739 337 14,800 6,700 20 30 4,970 Wet 281 57 5,600 1,100 10 90 1,550 6 Dry 767 362 15,300 7,200 0 40 2,880 Wet 72 0 1,400 0 60 40 840 7 Dry 742 339 14,800 6,800 20 20 4,320 Wet 550 209 11,000 4,200 50 50 7,600 8 Dry 0 326 0 6,500 0 20 1,300


Table S-23 Groundwater: Diversion Water Requirement (Current) Net Water





(m3/ha) Wet 440 152 7,300 2,500 10 70 2,480 1 Dry 0 350 0 5,800 0 70 4,060 Wet 262 28 4,400 500 10 70 790 2 Dry 787 373 13,100 6,200 0 70 4,340 Wet 272 42 4,500 700 10 70 940 3 Dry 771 359 12,900 6,000 0 70 4,200 Wet 203 3 3,400 100 10 70 410 4 Dry 782 370 13,000 6,200 0 70 4,340 Wet 87 0 1,500 0 30 50 450 5 Dry 739 337 12,300 5,600 0 70 3,920 Wet 281 57 4,700 1,000 10 70 1,170 6 Dry 767 362 12,800 6,000 0 70 4,200 Wet 72 0 1,200 0 30 50 360 7 Dry 742 339 12,400 5,700 0 70 3,990 Wet 550 209 9,200 3,500 10 70 3,370 8 Dry 0 326 0 5,400 0 20 3,780


Table S-24 Surface Water: Diversion Water Requirement (Proposed) Net Water





(m3/ha) Wet 440 152 8,800 3,000 40 60 5,3201 Dry 0 350 0 7,000 0 50 3,500Wet 262 28 5,200 600 50 50 2,9002 Dry 787 373 15,700 7,500 20 60 7,640Wet 272 42 5,400 800 50 50 3,1003 Dry 771 359 15,400 7,200 20 60 7,400Wet 203 3 4,100 100 50 50 2,1004 Dry 782 370 15,600 7,400 20 60 7,560Wet 87 0 1,700 0 80 20 1,3605 Dry 739 337 14,800 6,700 50 30 9,410Wet 281 57 5,600 1,100 80 20 4,7006 Dry 767 362 15,300 7,200 50 30 9,810



Net Water Requirement (mm)

Gross Water Requirement(m3/ha)

Cropping Pattern (%) HA Season

Paddy Upland Paddy Upland Paddy Upland


(m3/ha) Wet 72 0 1,400 0 80 20 1,1207 Dry 742 339 14,800 6,800 50 30 9,440Wet 550 209 11,000 4,200 40 60 6,9208 Dry 0 326 0 6,500 0 50 3,250


Table S-25 Groundwater: Diversion Water Requirement (Proposed) Net Water





(m3/ha) Wet 440 152 7,300 2,500 10 75 2,6051 Dry 0 350 0 5,800 0 75 4,350Wet 262 28 4,400 500 10 75 8152 Dry 787 373 13,100 6,200 0 75 4,650Wet 272 42 4,500 700 10 75 9753 Dry 771 359 12,900 6,000 0 75 4,500Wet 203 3 3,400 100 10 75 4154 Dry 782 370 13,000 6,200 0 75 4,650Wet 87 0 1,500 0 30 55 4505 Dry 739 337 12,300 5,600 0 75 4,200Wet 281 57 4,700 1,000 10 75 1,2206 Dry 767 362 12,800 6,000 0 75 4,500Wet 72 0 1,200 0 30 55 3607 Dry 742 339 12,400 5,700 0 75 4,275Wet 550 209 9,200 3,500 10 75 3,5458 Dry 0 326 0 5,400 0 75 4,050


Monthly Variations of Diversion Water Requirement by Hydrological Area

The following table shows monthly variations of diversion water requirement in each hydrological area (HA) based on Scenarios No.1 and No. 2. As for the surface water sources, the diversion water requirement in the northern area (HAs-1, 2, 3 and 8) is maximum in May, the beginning of wet-season irrigation. In the southern area (HAs-4, 5, 6 and 7) where annual precipitation is higher, meanwhile, it is maximum in November, the beginning of dry-season irrigation.

Table S-26 Monthly Variations of Diversion Water Requirement (mm) HA JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC1 81 82 40 - 313 202 0 19 0 - 83 64 2 183 174 52 - 204 46 40 0 0 - 204 149 3 173 164 57 - 233 74 17 0 0 - 201 144 4 185 174 46 - 150 29 27 0 0 - 199 152 5 239 222 0 - 139 0 0 0 0 - 269 211 6 244 226 11 - 213 0 90 169 0 - 288 215 7 243 222 0 - 115 0 0 0 0 - 268 212 8 74 73 37 - 317 224 129 20 0 - 83 59

Water Source: Surface Water Bodies

In the case of Fadama farming or small-scale private irrigation that mainly use sub-surface flows or groundwater, the diversion water requirement in the northern area (HAs-1 and 8) is maximum in May, the beginning of wet-season irrigation. In the central and southern areas (HAs-2, 3, 4, 5, 6 and 7), meanwhile, it is maximum in January, the mid-term of dry-season irrigation. In addition, farmers grow crops only in the dry season after flood recessions in the case of Fadama farming or small-scale private irrigation farming that use sub-surface flows as major water sources.



Table S-27 Monthly Variations of Diversion Water Requirement (mm) HA JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC1 101 103 50 - 148 111 0 4 0 - 104 80 2 119 114 39 - 61 8 10 0 0 - 105 90 3 111 107 43 - 73 22 3 0 0 - 103 86 4 120 114 35 - 28 5 5 0 0 - 101 92 5 126 118 0 - 44 0 0 0 0 - 80 98 6 130 120 11 - 22 0 26 70 0 - 92 100 7 129 118 0 - 36 0 0 0 0 - 79 99 8 92 92 47 - 151 126 72 4 0 - 104 74

Water Source: Sub-surface flows or groundwater

(3-7) Private Small Irrigated Farming

About 70 percepts of the area of private small irrigated farming locate in nationwide cultivated land. The remaining locates in flood plain and plant crops in dry season after flood recession as well as Fadama farming.

(3-8) Current Irrigation Water Demand

The following table shows water demands of surface water irrigation schemes, Fadama irrigation systems and a part of small-scale private irrigation systems with sub-surface flow water, and small-scale private irrigation systems with groundwater irrigation The overall water demand is 812MCM in the wet season and 872MCM in the dry season, and the total amount is 1,684MCM year-round. The total amount corresponds approximately to 0.6% of Nigeria’s surface water abundance 285,000MCM.

Table S-28 Current Irrigation Water Demand (MCM) Water Source Type Area (ha) Wet Season Dry Season Total

Surface Water Irrigation scheme 122,734 590 344 934Sub-surface Flow Fadama, partial Small-scale

private irrigation 93,000 0 271 271

Groundwater Small-scale private irrigation 90,000 222 257 479Total 305,734 812 872 1,684

1) Area where irrigation facilities have already equipped in ongoing irrigation schemes. Source: JICA Project Team

(3-9) Irrigation Water Demand of Proposed Scenario No.1

The overall water demand is 4,639MCM in the wet season and 10,219MCM in the dry season, and the total amount is 14,858MCM year-round. The total amount corresponds approximately to 5% of Nigeria’s surface water abundance 285,000MCM.

Table S-29 Irrigation Water Demand of Proposed Scenario No.1 (MCM) Water Source Type Area (ha) Wet Season Dry Season Total

Surface Water Irrigation scheme 1,200,000 4,351 8,750 13,101

Sub-surface Flow Fadama, partial Small-scale private irrigation

139,000 0 608 608

Groundwater Small-scale private irrigation 196,000 288 861 1,149

Total 1,535,000 4,639 10,219 14,858Source: JICA Project Team

(3-10) Irrigation Water Demand of Proposed Scenario No.2

The overall water demand is 9,667MCM in the wet season and 25,810MCM in the dry season, and the total amount is 35,477MCM year-round. The total amount corresponds approximately to 12% of Nigeria’s surface water abundance 285,000MCM.



Table S-30 Irrigation Water Demand of Proposed Scenario No.2 (MCM) Water Source Type Area (ha) Wet Season Dry Season Total

Surface Water Irrigation scheme 3,070,000 9,379 24,341 33,720

Sub-surface Flow Fadama, partial Small-scale private irrigation 139,000 0 608 608

Groundwater Small-scale private irrigation 196,000 288 861 1,149

Total 3,405,000 9,667 25,810 35,477Source: JICA Project Team

(3-11) Preliminary Consideration on Water Demand Variations of Scenarios No.1 and No.2 due to Climate Change

We consider impacts of climate change on water demand based on Climate Change Scenario No.1, which is set up tentatively in the Project. Taking projected air temperature variations into account, in this regard, we project and set the future reference PET derived from the fundamental reference PET multiplied by the coefficients of air temperature variation shown in the table below. Here, the coefficients of air temperature variation are calculated and obtained by the Hamon’s equation.

Table S-31 Coefficient of Air Temperature Variation HA-1 HA-2 HA-3 HA-4 HA-5 HA-6 HA-7 HA-8

Air Temp. Variation (oC) +2.5 +2.4 +2.4 +2.3 +2.1 +2.2 +2.2 +2.5 Coefficients of Air

Temperature Variation 1.168 1.160 1.160 1.153 1.139 1.146 1.146 1.168


Given the occurrence of Climate Change Scenario No.1, it is projected that the water demand will increase by nearly 15% in total on both Scenarios No.1 and No.2. As shown in Table S-32, water demand will increase more in the wet season rather than in the dry season. Particularly, the groundwater demand for small-scale irrigation is projected to increase most by 31%.

Table S-32 Variation of Water Demand due to Climate Change

Scenario No.1

Water Source Type Area (ha) Wet Season Dry Season Total

Surface water Irrigation schems 1,200,000 +23% +11% +15%

Sub-surface flow (Floodplain)

Fadama farming + some small-scale irrigation 139,000 0% +11% +11%

Groundwater Small-scale irrigated farming 196,000 +31% +14% +18%

Total 1,535,000 +24% +11% +15%

Scenario No.2

Water Source Type Area (ha) Wet Season Dry Season Total

Surface water Irrigation schems 3,070,000 +23% +11% +15%

Sub-surface flow (Floodplain)

Fadama farming + some small-scale irrigation 139,000 0% +11% +11%

Groundwater Small-scale irrigated farming 196,000 +31% +14% +18%

Total 3,405,000 +24% +11% +15%Source: JICA Project Team



4. Evaluation of Water Resources Potential

(1) Catchment Delineation

The joint effort of NIHSA and JICA Project Team on the review on the catchment delineation has been made through the course of the Phase-I of the project. The principles for delineation of Hydrological Area (HA, Sub Hydrological Area (SHA) and criteria for delineation of SHA have been discussed and been basically agreed.

Major change from HAs prepared in M/P1995 appears in Katsina area. There are only minor changes for other areas. Totally, 168 related SHAs have been delineated, three (3) of which are located completely outside of Nigeria. Some SHAs extend their areas to outside Nigeria. These SHAs are further sub-divided by national boundary of Nigeria, which results in 194 sub-divided SHAs in total. The aggregation of the portion of SHAs inside Nigeria for specific HA coincides with the HA boundary. The delineated SHAs are shown in Figure S-17.

127

151

107106

169

23

21

2535

34

10

32

33

70

166

168

102

101

858478

77

150

128

121

129

152

153

161

36

184

135

19

159

108

114

15

13

163

67

175177

130

162

64

65

167

4039

41

38

149

148

165

140

123 126

56

3012

170

63

185

136 116

20

31

97

94

194

186

189

193192

188

138

28

24

96

4544

55

18

27

22

134

133

137

187

183

182

157

160

154

124

125

145

142

99

95

105

115

113

112

111109

62

66

9

17

1614

53

1

8988

91

92

86

164

171

173

57

58

2

69

68

180174

181

176178

74

73

42

76

46

47

48

26

100

82

117

83

103

98

6054

53

49

52

71

110

6159

4

11

8

29

87

81120

3775

76

80

119

118

43

156

158

132

131

143

144

147

146

HA-8

HA-7

HA-6

HA-5

HA-4

HA-3

HA-2

HA-1

Main RiversWater Bodies

SHA BoundaryHA Bounadry

Source: JICA Project Team Note: The number in the map is not the code number of SHAs. The corresponding code number is presented in Annex-T 5-1.

Figure S-17 Delineated Boundary of Sub Hydrological Areas (SHAs)

The delineation of catchment (HA and SHA) was mainly based on the desk work with utilizing available information and data which have certain limitation of accuracy and spatial resolution. Considering the data source utilized, the spatial resolution of delineation could be as good as the order of 1/100,000 scale maps. The field verification was also limited for this work because of the limited resources and current security condition in Nigeria. Therefore, in future, it could be modified by NIHSA when it will be confirmed by the field works or more accurate information and data that the delineation is not correct. To do so in future, the GIS data and related data will be provided to NIHSA.

(2) Meteorological Condition

There are two available sources for meteorological data. One is the internal dataset available in




Nigeria, and another is the global dataset. The former is mainly managed by NIMET that is responsible agency for meteorological observation in Nigeria. The latter can be available from web-sites. Table S-33 summarizes the advantage and disadvantages of these data.

Table S-33 Advantage and Disadvantage of Available Meteorological Data Data

Source Data

Manager Summary Advantage Disadvantage

NIMET Synoptic Stations

NIMET

- Long-term observed data with reliable observation system

- Require cost for obtaining the data. NIMET recommended 27 priority synoptic stations with important parameters including daily precipitation for last 30years

- Most reliable and official information

- Daily precipitation available

- Only point observation data with 27 points are offered.

- Costly for obtaining full dataset

CRU-TS 3.11 BADC

- Gridded monthly data based on observed data by meteorological agencies in each country.

- Often used for climate-related study - Grid size = 0.5degree - Duration= 1901-2009 - Freely available from web-site

- Monthly time series data with medium spatial resolution

- Data outside Nigeria are also available

- No cost

- Effect of altitude not considered

Worldclim2 Robert J. Hijiman

- Gridded long-term averaged (1950-2000) monthly precipitation and air temperature based on observed data with correction for altitude

- Grid size = 0.5, 2.5, 5.0 and 10 minutes - Freely available from web-site

- High spatial resolution with consideration of effect of altitude


- No cost

- Only long-term averaged value available

GSMaP3 JAXA

- Gridded daily/hourly precipitation data based on satellite information such as TRMM

- Grid size = 0.25 degree - Duration =1998-2006 - Freely available from web-site

- High resolution in time and medium resolution in space


- No cost

- Bias correction could be required before using them

- Only recent data are available

NIMET: Nigerian Meteorological Agency, BADC: British Atmospheric Data Centre, JAXA: Japan Aerospace Exploration Agency Source: JICA Project Team

Considering the advantage and disadvantage on the available meteorological data, the following strategies on the usage of these data are set in the present project.

For the long-term analysis on assessment of availability of water resources covering the entire Nigeria and the related surrounding catchment areas, the gridded (2.5minites) monthly precipitation, air temperature and potential evapotranspiration (PET) are prepared based on CRU-TS3.1 and Worldclim. The duration of dataset prepared is 51years from 1959 to 2009.

Point observation data for daily precipitation by NIMET may be used for checking precipitation pattern within a month as well as frequency analysis for short-term heavy precipitation events for assessing overall flood condition.

The data from GSMaP might be used for flood analysis for limited specific pilot areas where the necessary information is available aside from precipitation data for the flood analysis in the later stage of the project, if necessary. It should be noted that GSMaP is available only from 1998 to 2006.

Based on the prepared the gridded (2.5minites) monthly precipitation, air temperature and potential evapotranspiration (PET)4, the annual precipitation and annual mean air temperature in Nigeria in the last 40years (1970-2009) are estimated at 1,150mm/year and 26.6degree Celsius in average, 1 University of East Anglia Climatic Research Unit (CRU). [Phil Jones, Ian Harris]. CRU Time Series (TS) high resolution gridded datasets, [Internet]. NCAS British Atmospheric Data Centre, 2008. Available from http://badc.nerc.ac.uk/view/badc.nerc.ac.uk__ATOM__dataent_1256223773328276 2 Hijmans, R.J., S.E. Cameron, J.L. Parra, P.G. Jones and A. Jarvis, 2005. Very high resolution interpolated climate surfaces for global land areas. International Journal of Climatology 25: 1965-1978. Available from http://www.worldclim.org/ 3 http://sharaku.eorc.jaxa.jp/GSMaP_crest/index.html 4 Hamon method has been applied for estimating PET. (Hamon, W.R.: Estimating potential evapotranspiration, Journal of the Hydraulics Division, Proceedings of the American Society of Civil Engineers, v. 87, p. 107–120, 1961.)


respectively. Figure S-18 shows the spatial pattern of annual precipitation and annual PET over the county. The annual precipitation varies from over 3,000mm in Niger delta area to about 400mm in the most northern part of the country. The annual PET is affected by altitude. In the high elevation area along the country border in the south-east as well as around Jos, the annual PET becomes small. The following table summarizes the spatially averaged annual precipitation, annual mean air temperature and annual PET for each HA.

Table S-34 Spatially Averaged Annual Precipitation, Annual Mean Air Temperature and Annual PET for Each HA

Entire country HA-1 HA-2 HA-3 HA-4 HA-5 HA-6 HA-7 HA-8

Annual P (mm/year) 1,148 767 1,170 1,055 1,341 2,132 1,541 2,106 610 Annual Mean T (degree Celsius) 26.6 27.4 16.5 26.0 26.8 26.7 26.5 26.9 26.5

Annual PET (mm/year) 1,337 1,419 1,318 1,290 1,338 1,325 1,314 1,338 1,347P:Precipitation, T:Air Temperature, PET: Potential Evapotranspiration Source: JICA Project Team

HA-8

HA-7

HA-6

HA-5

HA-4

HA-3

HA-2

HA-1

Annual Precipitation (mm/year)

3000

HA-8

HA-7

HA-6

HA-5

HA-4

HA-3

HA-2

HA-1

Annual PET(mm/year)

1600

Source: JICA Project Team Note: Average in 1970-2009 (40years) Figure S-18 Spatial Patterns of Annual Precipitation and Annual PET

The annual precipitation for the entire country tends to slightly decrease in the last 50years, and the rate is -1.7% in 50years. The annual mean air temperature for the entire country tends to increase with +3.0% in 50years.

Figure S-19 show the variation of annual precipitation by decades. One can see that 1960s was relatively wet (more precipitation) and 1970s-1980s was dry (less precipitation). 1990s-2000s became wet periods again. The magnitude of the fluctuation is much larger than the linear change rate of annual precipitation in 50years. On the other hand, annual mean air temperature has been increasing almost constantly without large fluctuation over five (5) decades.

Total (%) HA‐1(%) HA‐2 (%) HA‐3 (%) HA‐4 (%) HA‐5 (%) HA‐6 (%) HA‐7 (%) HA‐8 (%)

1960s 6.5 10.9 6.6 5.7 5.4 3.5 6.2 5.1 9.6

1970s ‐2.8 ‐3.6 ‐2.4 ‐2.1 ‐1.0 ‐2.2 ‐5.7 ‐2.8 ‐1.6

1980s ‐6.8 ‐10.2 ‐7.1 ‐4.4 ‐5.4 ‐5.0 ‐4.4 ‐4.8 ‐15.7

1990s 1.7 2.0 1.4 0.4 ‐0.1 1.6 3.7 1.2 3.4

2000s 1.4 0.9 1.5 0.4 1.1 2.1 0.2 1.4 4.3

‐20.0‐15.0

‐10.0‐5.0

0.05.0

10.015.0

Ann

ual Precipitaion

Differen

ce fo

rm Average in

19

60‐200

9 (%

)


Figure S-19 Variation of Annual Precipitation by Decades



The seasonal variation of precipitation and PET for each HA is presented in Figure S-20. In the figure, 80% dependable precipitation for each month as well as average monthly precipitation and PET are presented. There are clear dry and wet seasons in a year for the entire country, although there are two peaks of precipitation in a year in the southern HAs such as HA-5, 6 and 7. In the northern HAs, there is almost no precipitation during dry season.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

P 0.0 0.5 4.4 21.4 60.0 106.2 171.9 224.0 148.4 29.6 1.0 0.0

P80 0.0 0.0 3.3 8.0 33.1 74.3 135.1 170.1 109.3 12.1 0.7 0.0

PET 84.6 95.7 135.0 157.6 162.9 139.5 126.0 114.0 109.2 114.2 95.3 84.7

0

50

100

150

200

250

300

350

400

Precipitation

＆Ｐ

ＥＴ(m

m) HA‐１


P 2.3 5.6 22.5 63.8 131.5 164.0 200.0 241.8 236.5 93.3 7.1 1.9

P80 1.5 0.0 11.5 35.7 95.5 131.7 153.2 182.9 188.3 53.2 2.0 1.0

PET 96.1 102.6 129.2 134.3 131.5 114.5 110.5 103.6 99.5 103.9 98.5 93.6

0

50

100

150

200

250

300

350

400

Precipitation

＆Ｐ

ＥＴ(m

m) HA‐2


P 0.3 1.8 14.2 52.8 106.9 144.0 221.6 248.0 188.0 72.7 4.6 0.2

P80 0.1 0.0 6.3 30.9 81.3 111.6 174.4 203.3 149.1 47.7 2.3 0.1

PET 87.9 95.1 126.5 133.5 133.6 115.9 110.6 104.6 98.5 103.7 94.3 86.0

0

50

100

150

200

250

300

350

400

Precipitation

＆Ｐ

ＥＴ(m

m) HA‐3


P 3.2 6.3 32.4 79.2 161.5 178.9 213.3 260.1 251.1 140.9 12.9 1.4

P80 1.6 0.0 13.6 50.2 130.9 148.1 163.7 202.1 206.4 99.1 6.6 0.5

PET 100.2 106.2 131.4 130.9 128.1 113.8 111.8 107.2 102.3 106.3 102.8 97.1

0

50

100

150

200

250

300

350

400

Precipitation

＆Ｐ

ＥＴ(m

m) HA‐4


P 20.7 43.2 86.5 148.7 238.7 313.3 305.8 247.7 360.2 265.8 77.3 24.4

P80 7.4 0.0 57.1 103.5 188.3 256.9 227.9 179.2 280.5 191.3 41.7 7.0

PET 106.7 107.4 125.1 121.5 121.8 110.8 108.1 104.9 101.8 105.6 106.2 105.4

0

50

100

150

200

250

300

350

400

Precipitation

＆Ｐ

ＥＴ(m

m) HA‐5


P 10.8 30.5 79.4 133.1 184.4 222.5 217.6 152.8 257.2 190.6 45.8 15.6

P80 4.0 0.0 46.5 88.9 140.5 175.8 146.1 83.2 192.5 132.0 19.2 3.7

PET 106.1 106.7 125.3 121.2 121.8 110.7 106.3 101.9 99.8 104.6 105.3 104.5

0

50

100

150

200

250

300

350

400

Precipitation

＆Ｐ

ＥＴ(m

m) HA‐6


P 17.6 37.5 86.8 146.6 240.2 284.8 305.1 290.9 333.8 274.9 69.3 18.2

P80 4.0 0.0 58.5 112.0 197.0 236.0 238.3 232.1 269.3 212.4 34.1 3.9

PET 108.6 108.9 125.7 121.0 122.5 111.7 109.7 106.0 103.6 107.1 107.2 106.3

0

50

100

150

200

250

300

350

400

Precipitation

＆Ｐ

ＥＴ(m

m) HA‐7


P 0.0 0.1 0.9 10.5 38.6 73.1 167.8 206.4 96.5 15.5 0.0 0.0

P80 0.0 0.0 0.4 5.5 22.6 46.5 120.3 153.2 61.9 6.0 0.0 0.0

PET 73.8 82.7 119.9 146.7 159.3 142.2 125.8 112.5 109.1 111.2 88.8 75.0

0

50

100

150

200

250

300

350

400

Precipitation

＆Ｐ

ＥＴ(m

m) HA‐8

Source: JICA Project Team Note: P80=80% dependable monthly precipitation, Duration of date used =1970-2009 (40years)

Figure S-20 Seasonal Variation of Precipitation and PET




(3) Surface Water Resources

(3-1) Available Hydrological Data

In the present project, the available hydrological data have been collected in collaboration mainly with NIHSA. By integrating the collected hydrological data, the data for monthly discharge at 101 stations are arranged. The followings can be observed on the availability of the data through the inventory list of the hydrological data.

Along the Niger River and Benue River as well as Hadejia-Jammare-Komadugu-Yobe River system, long-term daily discharge data are available in general. However, many of them are strongly affected by operation of significant storage dams.

For other areas, only monthly data for limited time periods are available in general. For the stations along Niger River and Benue River outside Nigeria, only monthly data are

available. For HA-6, available discharge data are very limited.

Figure S-21 shows the change in number of hydrological stations with available monthly and daily data. The numbers of stations with available hydrological data becomes maximum from 1970s to 1980s. However, after 1980s the numbers gradually decreases.

0

10

20

30

40

50

60

70

80

1914 1924 1934 1944 1954 1964 1974 1984 1994 2004

Num

ber of Hydrological Station

s

Year

Arranged CompleteMonthly Data Available

Arranged Monthly DataAvailable (incl. partial data)

0

10

20

30

40

50

60

70

80

1914 1924 1934 1944 1954 1964 1974 1984 1994 2004

Num

ber of Hydrological Station

s

Year

Complete Daily Data Available

Daily Data Available (incl. partial data)


Figure S-21 Change in Number of Hydrological Stations with Available Monthly and Daily Data

(3-2) Surface Water Resources Potential in Quasi-Natural Condition

It is always better to use directly observed data, if they are available and their quality is good. However, in the present project there are not enough discharge data in term of space and time for proper assessment of water resource. Furthermore, the observed data at many stations are disturbed by operation of large dams. A long-term rainfall-runoff simulation model has been introduced in order to obtain supplemental information on runoff condition in space and time, especially for the quasi-natural condition5 without effect of the large storage dams. The model can also be used for exploring the effect of climate change on runoff.

In the present project, a monthly-basis soil-moisture accounted model, which is called as the Thornthwaite monthly water balance model6 has been selected and were applied with semi-distributed manner7 , 8 , 9 in a catchment for the long-term rainfall-runoff model. The model parameters are calibrated against the observed discharge at the selected hydrological stations. 5 It is not possible for us to know actual natural condition which has no influence of human activity. The quasi-natural condition is defined as the condition without influence of significant storage dams and abstraction in the present project. 6 G.J. McCabe and S.L. Markstrom: A Monthly Water-Balance Model Driven by a Graphical User Interface, USGS Open-File Report 2007-1088, 2007. 7 Moore, J.W. Trubilowicw and J.M. Buttle: Prediction of Streamflow Regime and Annual Runoff for Ungauged Basins using a Distributed Monthly Water Balance Model, J. of the American Water Resources Association, Vol.48, No.1, pp.32-42, 2012. 8 C. Gregory Knight, Heejun Chang, Marieta P. Staneva & DeyanKostov : A Simplified Basin Model For Simulating Runoff: The Struma River GIS,The Professional Geographer, 53:4, 533-545, 2001 9 FAO: Water Resources and irrigation in Africa, available from http://www.fao.org/nr/water/aquastat/watresafrica/index4.stm


The simulated results are used for estimation of surface water resources potential in quasi-natural condition. The simulated results cover the entire Benue river basin, the Niger river basin in the downstream catchment from Malanville in Benin, and other catchment areas whose generated runoff come into Nigeria (see Figure S-22). To estimate surface water resources potential comprehensively, it is necessary to give the discharge at Malanville as a boundary condition. The observed discharge at Malanville is available after 1970s. Therefore, it is decided to analyze the simulated runoff from 1970 to 2009 (40years), although the rainfall-runoff simulation was conducted from 1960 to 2009 (50years).


Figure S-22 Coverage Area of Long-term Rainfall-Runoff Simulation Model

Figure S-23 show spatial distribution of the average annual runoff yield. The average annual runoff yield (height) varies significantly across the county. In the most northern part of the county, the runoff yield is less than 20mm/year, whereas it becomes more than 1,000mm/year in the southern end.

HA-8

HA-7

HA-6

HA-5

HA-4

HA-3

HA-2

HA-1

Annual Runoff (mm/year)

1000

Source: JICA Project Team Note: Duration of data used =1970-2009 (40years)

Figure S-23 Spatial Distribution of Average Annual Runoff Yield




Figure S-24 shows the long-term averaged water balance in terms of annual total runoff volume across Nigeria.

HA-8

HA-7

HA-6

HA-5

HA-4

HA-3

HA-2

HA-1

26,230

34,220

270

19060

+7,840

62,31098,420

+27,910

55,570

15,120

+27,730

20,710

380

160,730

167,760

207,410

+32,060

+39,650

+7,030

23,890

82,350

+58,460

680

40,120

27,870

+28,470

1,380

1802,040

1,420560


Table S-35 Comparison between Surface Water Resources Potential Evaluated in M/P1995 and that in the Present Project

Estimated Potential Hydrological Area 1995 M/P

(MCM/year) Present Project(MCM/year)

Remarks

HA-1 22,400 34,200 Outlet of HA-1, including water from outside of Nigeria HA-2 32,600 28,100 Outlet of HA-2, including water from outside of Nigeria

HA-3 & 4 83,000 98,400 Outlet of HA4,including water from outside of Nigeria

HA-5 & 7 85,700* 89,400* Including water from outside of Nigeria *Delta area I HA-5 (39,600MCM/year) is excluded. HA-6 35,400 40,200

HA-8 8,200* 6,900**(1,400)***

*Not outlet of HA-8, but the sum of available water at key stations **Sum of runoff yield excluding loss along rivers ***Outlet of HA-8

Total 267,300 297,200*(291,700)***Excluding delta area in HA-5 (39,600MCM/year) **In case that water resources potential in HA-8 is 1,400MCM/year.

Source: M/P1995 and JICA Project Team

(3-3) Available Surface Water Resources in Quasi-Natural Condition

There are clear dry and wet seasons in Nigeria. The usable water in dry season with stable manner is much smaller than the annual average discharge in quasi-natural condition. In order to evaluate the stably usable surface water in quasi-natural condition, the following indicators were computed at the representative points. The computed these values are presented in Figure S-25.

QMAY80%Y - 80% year dependable discharge in May - According to the irrigation water demand in wet season shown in Section 3, the demand is

the highest in May. Considering this, this indicator represents the available water for irrigation in wet season with 80% reliability after subtracting minimum stream flow requirement and the demand of other water users with higher priority such as municipal water supply.

Q97DS90%Y - 90% year dependable Q97DS (Q97DS: 97 percentile daily discharge for a single year, which is

usually called as drought discharge, [suffix d represents daily, suffix s represents single year])

- This indicator represents a drought condition of river flow.

The QMAY80%Y is large in the central and southern areas such as Benue River and its tributaries, Cross River, which means that there is relatively high potential for irrigation water in rainy season cultivation without storage dams. In the northern area, the QMAY80%Y is almost zero, which shows much less potential for irrigation water use even in wet season without storage dams.

The Q97DS90%Y is 2-5% of average discharge in the central and southern areas in general. However, in the northern part of the country, it is almost zero in many places, which means that there is almost no stably usable water throughout a year in quasi-natural condition. In the northern area, it is inevitable to install storage dams for stable use of surface water throughout a year.




HA-8

HA-7

HA-6

HA-5

HA-4

HA-3

HA-2

HA-1

*** : Average Monthly Discharge(***) : 80% Year Dependable QMAY: 90% Year Dependable Q97 (97 Percentile Discharge)Unit: m3/s

832(23)

1,085(32)

8.4(0) 6.1

(0)1.9

(0)

1,976(110)

3,121(808)

1,762(222)

480(304)

657(39)

12(0.6)

5,097(992)

5,320(1,034)

6,577(1,594)

757(463)

2,611(1,038)

22(0.7)

1,272(117)

884(87)

44(0.7)

5.7(0)

65(1.2 )

45(1.4)

18(0.6)

0.2(0)

12(10)

6.0(0)

4.1(0.1)

101(23)

2.5(0.1)

Source: JICA Project Team Note: Duration of data used =1970-2009 (40years)

Figure S-25 Average Discharge, QMAY80%Y and Q97DS90%Y

(3-4) Preliminary Discussion of Effect of Climate Change on Runoff

In order to explore the possible change in climate conditions in future, the statistically downscaled output of GCMs, which is provided by CCAFS10, are analyzed. The statistical downscaling as well a bias correction was conducted utilizing the spatial distribution of parameters provided by Worldclim dataset. The downscaled data for A

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